Here's some random monsters I've made. A lot of these ideas are variations on stuff that I've seen on brickshelf ( there's a credit list in bs gallery of my favourite creature builders )
Jaden : the heads are from a few different sets. Frankenstein and the Werewolf are from the monsters line from the Studios line which also has a great vampire and Egyptian mummy. the 'horrible orcs' picture is: gringotts goblin ( harry potter ), yoda ( some space movie ), and doby ( harry potter )
jonathon : Franky is a combo between Hagrid's body and Studios System theme Frankentein head ( see above link )
when I made this cthulhu there wasn't any combo of the red lion's body and octopus head that I had seen, and seemed like such a good match. it's a real easy fun creature to make, and makes good use out of those odd body pieces. a search on brickshelf for cthulhu reveals quite the affinity between lego builders and squidy monsters